Light Microscope

• A light microscope can be used for multiple things
  • Cell & tissue identification
  • Check for foreign organisms
  • Size, measurements of structures
• Light microscopes can barely make out organelles
• They have a low magnification and resolution
  • Magnification - the degree which an image of an object is enlarged
  • Resolution - how far two things have to be apart before they can be seen as two separate things
• Make sure to know each part of the light microscope and its function

Determining Cell Diameters

1. Use the light microscope to find the cell under low and high power
2. Calibrate the eye piece graticule
   1. Place a micrometer slide on the stage of the microscope
   2. Focus on the micrometer scale using the low power objective lens
   3. Move the slide and rotate the eyepiece to align the scales of the eyepiece graticule and the micrometer scale in the field of view
   4. Count the number of divisions on the eye piece graticule and compare them to a known length on the micrometer scale to find the length of one eyepiece unit
   5. Repeat steps a-c with the medium power and high power objective lens
3. Count number of graticule units
4. Convert eye piece graticule units to microns using calibration
5. Measure cell diameter at different positions

• Image size is found using a ruler

Cheek cell - Microscope slide

• Using cotton buds, rub on the inside part of your cheek
• Rub the cotton bud on a glass slide
• Add a few drops of methylene blue (stain)
• Cover with a cover slip